The redundant license file (by default named lservrlf) is the key to the redundant license server pool. This file is created by the rlftool or WRlfTool utility (or WlmAdmin calling WRlfTool), and defines which license servers make up the redundant license server pool as well as how many tokens of which licenses are distributed among those license servers. Each computer on which a redundant license server resides will have a copy of this file.
Each license server in the redundant license server pool must be started with a copy of the redundant license file in the same directory in which the license server resides in order to come up as a redundant license server. (Or the license server -rlf startup option can be used to specify the location of the redundant license file.)